1. Field of the Invention
This disclosure relates to processing of packets in wireless network communications and, more particularly, to a system and method for determining a transmission order of packets in a node in a wireless communication network while considering quality of service requirements for the packets in the network.
2. Description of the Related Art
In networked communication, two or more nodes communicate information to each other using packets of data. One type of network is a mobile ad hoc network (MANET). Referring to FIG. 1, physically, a MANET 50 may include a number of geographically distributed, potentially mobile nodes 52, 54, 58 transmitting and receiving information using one or more frequency ranges or radio channels. Compared with other types of networks, such as cellular networks or satellite networks, MANETS frequently lack fixed infrastructure. The network is formed of mobile (and potentially stationary) nodes, and may be dynamically created or modified as the nodes communicate with each other. The network does not depend on any particular node and dynamically adjusts as some nodes join or others leave the network.
In a potentially hostile environment where a fixed communication infrastructure is unreliable or unavailable, such as in a battle field or in a natural disaster area struck by earthquake or hurricane, a MANET can be quickly deployed to provide much needed communications. Due to the lack of a fixed infrastructure, nodes should self-organize and reconfigure as they move, join or leave the network. All nodes may be essentially the same, and there is no natural hierarchy or central controller in the network. All functions therefore are distributed among the nodes. Nodes are often powered by batteries and have limited communication and computation capabilities. Also, the distance between two nodes that desire to communicate may be greater than the radio transmission range of a single node, and so a transmission between a source node 52 and a destination node 54 may have to be relayed by other core nodes 58 as shown by communication line 56. Consequently, a MANET typically has a multi-hop topology, where a piece of communication “hops” from one node to another, and the topology of the network itself changes as the nodes move around, enter, or leave the network.
The network topology changes arbitrarily as the nodes move. Data information is subject to becoming obsolete if the data takes too long to reach its destination. Different nodes often have different views of the network, both in time (information may be outdated at some nodes but current at others) and in space (a node may only know the network topology in its neighborhood and not far away from itself).
Because of these unique requirements, routing data through nodes in these networks is very different than routing in other networks. Gathering fresh information about the entire network is often costly and impractical. Some routing protocols are reactive (on-demand) protocols. That is, they collect routing information only when necessary and only to destinations to which they need routes, and do not maintain unused routes. In this way the routing overhead may be reduced compared to pro-active protocols, which maintain optimal routes to all destinations at all time.
MANETs may need to satisfy certain Quality-of-Service (QoS) routing requirements. In such requirements, there is a guarantee by the network to provide data applications with sufficient network resources so that they can function within pre-specified service metrics such as network delay, delay variance or jitter, probability of packet loss, etc. For example, video and audio data applications have different QoS requirements. This disclosure describes an improvement over prior art systems.